Section 73 applications – more cases and more clarity

In the recent decision in R (Atwill) v New Forest National Park Authority [2023] EWHC 625 (Admin), the High Court decided that the local planning authority had unlawfully granted a variation to a planning permission pursuant to section 73 of the Town and Country Planning Act 1990.

The case reaffirms the decisions handed down in recent cases on section 73 applications and sheds further light on the considerations that need to be borne in mind by developers and local authorities when dealing with this type of application.

Why was the case brought before the Court?

The local planning authority (LPA) had granted planning permission under section 73 of the Town and Country Planning Act 1990 (the Act) allowing a previous planning permission for a "dwelling; detached garage with office over; sewage treatment plant; demolition of existing dwelling and outbuilding" (the 2018 permission) to be varied (the 2021 variation).

In 2020, the interested party (IP) built a replacement dwelling which failed to comply with the conditions set out in the 2018 permission.

The LPA recognised that the new dwelling was not compliant with the 2018 permission and had issued an enforcement notice (EN) in relation to the same. The IP submitted an appeal against the EN.

Mrs Atwill (the Claimant), who lived close to the application site, had previously raised several concerns with the LPA, including the fact that the 2018 permission had not been lawfully implemented and that the development that had been carried out was unlawful. The Planning Inspectorate decided to delay issuing a decision in relation to the EN until the Court determined the Claimant's claim.

What did the Claimant argue?

The Claimant set out no fewer than seven grounds for challenging the decision to grant the 2021 variation.

First, they argued that the 2018 permission had lapsed. Works had not properly ‘begun’, given that the works that had been undertaken were unlawful. The 2021 variation was not for retrospective planning permission and a condition was applied to it, which had the effect of permitting the development to commence beyond the time limit set out in the 2018 permission. This would not be permissible if the 2018 permission had expired as a result of not being lawfully implemented.

Secondly, the LPA failed to consider the IP’s inability to implement the 2018 permission. Even if the 2018 permission was still extant, the discrepancies between the plans and the completed works meant that the 2018 permission had not been implemented as the development was not in accordance with the relevant plans.

The third ground argued that the IP had failed to attach certain conditions under the 2018 permission and therefore, the 2021 variation was unlawful.

The Claimant argued, under the fourth ground, that the LPA had incorrectly included a condition that was based on the unlawful development, not that which would have been lawful under the 2018 permission.

The fifth ground of challenge is topical, given recent case law which has been laid down on the subject. It concerned an argument that the LPA had unreasonably identified the amendments proposed under the 2021 variation to be “minor material amendments”.

Under ground six, the Claimant sought to argue that a new consultation should have been carried out ahead of the 2021 variation and, further, that the IP had failed to comply with its statutory duty under section 72 of the Conservation and Heritage (Listed Buildings and Conservation Areas) Act 1990.

The Claimant’s seventh and final ground asserted that the lighting scheme for the development was unclear and, as such, the conditions were unimplementable and ultimately unlawful. The lighting scheme was relevant due to a policy which prevented the erosion of rural darkness.

What was the LPA's argument?

On the first ground, the LPA argued that section 73 had a broad scope and that once development had started, section 73 is available immediately. As such, the question of whether or not a variation should be granted is a matter of planning judgment.

The LPA also contended, in relation to ground two, that the 2018 permission was implementable in accordance with its plans. Ultimately, it is a matter for the local authority to decide whether changes to a granted planning permission were material or not.

On ground three, the LPA argued that even though the condition was removed from the 2021 variation, a condition imposed through a separate retrospective 2019 planning permission relating to a garage would apply instead.

Dealing with the fourth ground, the LPA argued that no sensible reader would infer that the reference to the ‘as-built’ scheme would give the scheme an implied planning permission.

Regarding the Claimant’s ‘minor material amendment’ argument under ground five, the LPA argued that this is no longer to be considered, by virtue of recent case law.

In relation to ground six, it stated that the amended proposals under the 2021 variation discharged concerns from previous consultations and, therefore, there was no need for the LPA to re-consult.

Finally, for the seventh ground, the LPA noted that, on a proper reading of the plans, there was no ambiguity or conflict between conditions.

What did the court say?

On ground one, the Court agreed with the Claimant, stating that when determining whether development has commenced, any operations relied on must be ones which can properly be said to be undertaken pursuant to the initial planning permission.

The Court also agreed that section 73 related to 'amendments' to a previous 'live' planning permission.  If development was not lawfully commenced under that previous planning permission and the time period for implementation under it had expired, the previous planning permission would not be 'live' and therefore could not be amended. This means that in the Atwill case, the 2021 variation was unlawful, because it sought to extend the time period for implementation, even though the 2018 permission was no longer 'live'.

The Court considered the second ground to be, at heart, a public law challenge with a basis in irrationality and/or an alleged failure of the LPA to consider relevant facts. The judge emphasised that the burden for the Claimant was therefore high. Nevertheless, the evidence in support of the Claimant's second ground was, in the judge's view, "simply overwhelming."

The Court dealt with the third ground briefly, agreeing with the Claimant that the LPA failed to include a condition relating to garage use. The LPA could not rely on Class E use under Schedule 2, Part 1 of the Act, as the garage had not been built as a consequence of permitted development rights.

The Court explained, when considering the fourth ground, that section 73 decisions must relate to existing planning permissions and the conditions which they intend to vary. They cannot be used as an enforcement tool, as seems to have been the LPA's intention here.

The fifth ground dealt with the question of 'minor material amendments'. The Court noted that following the decision in the recent Armstrong case, it is incorrect to seek to limit the scope of section 73 applications to 'minor material amendments'.

However, the Armstrong case also confirmed the rule set out in the case of Finney that any variation under section 73 must not change the operative part of the existing planning permission. Here, the 2021 variation's operative part referred to "details of lighting", which was different to the 2018 permission and, in the Court's view, more than a de minimus difference.

The only ground the Claimant did not succeed on was ground six. The decision as to whether a further consultation was necessary was a question for the LPA and a matter of planning judgment.

On the final ground, the Court agreed with the Claimant that there was a "significant degree of confusion" between the conditions in question and, as such, an unresolved tension that needed to be rectified.


The case is useful in that it reaffirms the decisions in Armstrong and Finney and cements the fact that ‘minor material amendment’ considerations are a thing of the past. The key is to look at whether any variations conflict with the operative part of a planning permission when deciding to grant section 73 approvals.

The judge also provides a useful run-through of the case law on what development means, at which point commencement takes place and what amounts to unlawful development.

For more on the cases of Armstrong and Finney and their impact on section 73 applications, please do take a look at our recent article on the subject, which you can find here.

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